Final Fantasy 8’s sound effects are stored within two files. The audio.dat contains the actual wav files, compressed as 4-bit ADPCM. The audio.fmt file is a locator for sounds in the dat.
FMT File Structure
The FMT is headed by 4 bytes representing the number of sound file headers in the rest of the FMT file, then by a 36 byte header that isn’t interesting.
Each sound header (beginning with the first at 0x28) either contains 70 bytes if it represents a valid sound file, or 38 bytes if it’s a blank entry (those 38 bytes are all 0x0)
Each sound header representing a valid sound file contains the following structure:
| Offset | Size | Data |
|---|---|---|
| 0x00 | 4 bytes | Size of wav file in the dat. |
| 0x04 | 4 bytes | Offset of wav file in the dat. |
| 0x08 | 12 bytes | Unknown. If first byte is 0, the other 11 are always 0. Probably some kind of looping metadata. |
| 0x14 | 18 bytes | Microsoft WAVFORMATEX header for the wav file. |
| 0x26 | 2 bytes | Samples per block |
| 0x28 | 2 bytes | Number of ADPCM coefficients (used for compression, should always be 7). |
| 0x2A | 28 bytes | Standard Microsoft ADPCMCoefSets. |